Algebra 1
posted by Britt on .
solve: log8(w6)=2log8(w+15)
note: the 8 is to be little at the bottom right corner of log

since 64 = 8^2, then using base8 logs, we have
log(w6) = log(64)log(w+15)
(w6) = 64/(w+15)
(w6)(w+15) = 64
w^2 + 9w  154 = 0
w = 1/2 (9±√697)
scrap the negative value (why?) 
because the answer has got to be a real number which is not a negative number

how do you get 1/2 as a solution?

So technically there would be no solution right?

So, technically, the solution is
x = 1/2 (9+√697) = 8.70
where does the 1/2 come from? Think back ... back ... back to Algebra I and the quadratic formula. 
the quadratic formula is b+radical b^24ac/a

SO HOW DO YOU GET 1/2 FORM THAT?

Britt, when Steve and I went to school, the quadratic formula used to be
(b ± √(b^2 4ac)/(2a) or
(1/2) (b ± √(b^2 4ac)/a , thus the 1/2
I was not aware of any recent changes to the formula.